Gas chromatography/mass spectrometry and HPLC (high pressure liquid chromatography) will be used to measure changes in the levels of various neurochemicals and their metabolites in the brain, cerebrospinal fluid (CSF), and serum of rabbits infected with the African trypanosome, Trypanosoma brucei gambiense. These New Zealand white rabbits become very debilitated and often somnolent within 4 weeks after infection with this protozoan. Compounds to be measured include noradrenaline, dopamine, 5-hydroxytryptamine, 5-hydroxyindoleacetic acid, 5-hydroxytryptophol, 3-indole acetic acid, 3-indole ethanol (tryptophol), 3,4-dihydroxyphenylacetic acid (DOPEC), homovanillic acid (HVA), and vanillylmandelic acid (VMA). In addition to whole brain preparations, the following particular tissues and fluids will be studied: the choroid plexuses, the hypothalamus, brain stem, microvessels, and CSF. Changes in levels of these compounds will be monitored at various times during infection.